Grad Stats Online Quiz Q&A

If we calculated an effect size and found it was r = .42 which expression would best describe the size of effect?

medium to large

A correlation of .7 was found between time spent studying and percentage on an exam. What is the proportion of variance in exam scores that can be explained by time spent studying?

.49

Which of the numbers below might IBM SPSS report as 10.574 E−05?

0.00010574

Given a test is normally distributed with a mean of 30 and a standard deviation of 6: What is the probability that a single score drawn at random will be greater than 34?

0.2524

If Pearson's correlation coefficient between stress level and workload is .8, how much variance in stress level is not accounted for by workload?

36%

Rank the score of 5 in the following set of scores: 9, 3, 5, 10, 8, 5, 9, 7, 3, 4

4.5

How much variance has been explained by a correlation of .9?

81%

Which of the numbers below might IBM SPSS report as 8.96 E+03?

8960.0

Approximately what percentage of people would have scores lower than an individual with a z-score of 1.65 in a normally distributed sample?

95%

The covariance is:

A measure of the strength of relationship between two variables. Dependent on the units of measurement of the variables. An unstandardized version of the correlation coefficient.

Assuming the assumptions of parametric tests are met, non-parametric tests, compared to their parametric counterparts:

Are more conservative. Are less likely to accept the alternative hypothesis. Have less statistical power.

R2 is known as the:

Coefficient of determination.

When items on a questionnaire appear to correspond to the construct that the questionnaire claims to measure it is said to have:

Content validity

Ordinal level data are characterized by:

Data that can be meaningfully arranged by order of magnitude.

For what is the 'variable view' in IBM SPSS's data editor used?

Defining characteristics of variables.

The t-test tests for:

Differences between means Whether a correlation is significant Whether a regression coefficient is equal to zero

The degree to which a statistical model represents the data collected is known as the:

Fit

A researcher measured the same group of people's physiological reactions while watching horror films and compared them to when watching erotic films, and a documentary about wildlife. The resulting data were skewed. What test should be used to analyse the data?

Friedman's ANOVA

For which regression assumption does the Durbin-Watson statistic test?

Independence of errors

A researcher measured people's physiological reactions while watching a horror film and compared them to when watching a comedy film, and a documentary about wildlife. Different people viewed each type of film. The resulting data were normally distributed and the variances across groups were similar. What test should be used to analyse the data?

Independent analysis of variance

Which of the following statements about outliers is not true?

Influential cases will always show up as outliers.

An experimenter measured 30 children's IQ. He then rank-ordered the children and assigned them a score from 30 (most intelligent) to 1 (least intelligent) to create a new variable. Does this new variable consist of:

Ordinal data

Which of the following are assumptions underlying the use of parametric tests (based on the normal distribution)?

Some feature of the data should be normally distributed. The samples being tested should have approximately equal variances. The data should be at least interval level.

Variation due to some genuine effect is known as:

Systematic variation

Which of the following is not a transformation that can be used to correct skewed data?

Tangent transformation

If we use the mean as a model, what does the variance represent?

The average error between the model and the observed data.

What does the error bar on an error bar chart represent?

The confidence interval around the mean. The standard error of the mean. The standard deviation of the mean.

Differences between group means can be characterized as a regression (linear) model if:

The experimental groups are represented by a binary variable (i.e. coded 0 and 1).

Which of the following is the least affected by outliers?

The median

If we were to pull all possible samples from a population, calculate the mean for every sample, and construct a graph of the shape of the distribution based on all of the means, what would we have?

The sampling distribution of the mean

What is b0 in regression analysis?

The value of the outcome when all of the predictors are 0.

What symbol represents the test statistic for the Mann-Whitney test?

U

When variances across independent groups are unequal, which of the following is not an appropriate course of action?

Use Friedman's ANOVA.

A researcher measured the same group of people's physiological reactions while watching horror films and compared them to when watching erotic films. The resulting data were skewed. What test should be used to analyse the data?

Wilcoxon signed-rank test

A researcher was interested in stress levels of lecturers during lectures. She took the same group of 8 lecturers and measured their anxiety (out of 15) during a normal lecture and again in a lecture in which she had paid students to be disruptive and misbehave. The data were not normally distributed. Which test should she use to compare her experimental conditions?

Wilcoxon signed-rank test

Which of these statements describes a Bonferroni correction?

You apply a criterion for significance based on the usual criterion for significance (.05) divided by the number of tests performed.

What is the relationship between the sum of squared errors (SS), the sample size (n) and the variance (s2)?

s2 = SS / (n-1)

Which of the following is not a type of post hoc test?

Cramér

A researcher measured people's physiological reactions to horror films. He split the data into two groups: males and females. The resulting data were normally distributed and men and women had equal variances. What test should be used to analyse the data?

Independent t-test

Which of the following statistical tests allows causal inferences to be made?

None of these, it's the design of the research that determines whether causal inferences can be made.

A researcher was interested in stress levels of lecturers during lectures. She took the same group of 8 lecturers and measured their anxiety (out of 15) during a normal lecture and again in a lecture in which she had paid students to be disruptive and misbehave. What test is best used to compare the mean level of anxiety in the two lectures?

Paired-samples t-test

Levene's test tests whether:

The variances in different groups are equal.

Twenty-one cats were given 300g of tuna each. The time in seconds was measured until they had eaten all of the tuna: 16, 18, 18, 22, 22, 23, 23, 24, 26, 29, 32, 34, 34, 36, 36, 42, 43, 46, 46, 49, 57 Compute the median. Compute the lower quartile. Compute the upper quartile. Compute the interquartile range.

22.5 seconds

The owner of the large chain of coffee shops called 'MoonBucks' decided to calculate how much revenue was gained from lattes each month in a nationwide sample of 2445 cafés. To measure the variance of revenue gained from lattes, he computes SS = 351,936 for this sample. What are the degrees of freedom for variance? Compute the variance. Compute the standard deviation.

2444

Which of the following best describes the variable 'Gender'?

All of the possible answers are correct: between group variable, grouping variable, coding variable